1. Field of the Invention
The present invention relates to prefabricated load-bearing wall panels.
2. Description of the Prior Art
Prefabricated building components, which are manufactured at one site and then transported to the construction site to be assembled, have proved quite useful in the construction industry. The use of prefabricated building components in this manner is favored because of the substantial reduction in labor costs in both the manufacturing and assembly processes. Another construction method employing building components is also quite cost effective. However, in this method the components are not completely prefabricated but are finished at the job site just prior to assembly.
Examples of such building components and these methods of construction are well known. United States Pat. No. 4,185,423 shows a lightweight building module in which a portion of the support columns for each module is embedded in concrete to provide an outer concrete face for the module. U.S. Pat. No. 2,497,887 also shows a wall panel and construction method where the panels are preformed before assembly of the building unit and in which a portion of the supporting columns for each panel is embedded in concrete. This type of building panel design is also shown in U.S. Pat. No. 2,703,003, which shows a wall panel having a lattice secured directly to a plurality of support columns with a concrete panel formed over the lattice and a portion of each column.
Forming panels as described in the above three patents places considerable stress on the concrete when the support columns are called upon to carry the weight of the building. Since at least a portion of the columns is embedded in the concrete, the concrete must compress or fail when the support columns are placed in compression. Similarly, if the support columns are placed in tension, the concrete must likewise tense with the columns or fail. To avoid these problems, the concrete should be secured to the support columns so that the concrete does not carry the weight of the structure. Devices have been conceived for resiliently securing wall panels to load-bearing wall columns. Examples of such devices are shown in U.S. Pat. No. 1,963,609, U.S. Pat. No. 1,940,933, U.S. Pat. No. 2,909,821, and U.S. Pat. No. 3,232,018. The devices of these patents are resilient clips upon which wall panels are hung in spaced relation from wall columns or studs.
Prior art prefabricated wall panels have been constructed with angle iron connectors or clips between the studs and a thin slab of concrete. These connectors consisted of metal L-shaped brackets extending from metal studs and welded to a reinforcing mesh embedded in the concrete panel. This design was found to be unsatisfactory because a normal shear load upon the wall panel caused the connectors to deform or fail, thus permanently damaging the panel unit. In addition, the connectors did not act to transfer loads to the slab of concrete in a manner that caused load to be picked up by the slab. The concrete slab tended to fail in the region of the connection.
Although not specifically related to prefabricated concrete panels, other patents of interest (showing various panels and means for securing panels to studs) are shown in the following U.S. patents:
______________________________________ Inventor U.S. Pat. No. ______________________________________ Duphiney 1,578,964 Glass 2,121,962 Deutsch 2,192,183 Fromson 2,558,946 Monk, Jr. 3,162,982 Lanctot 3,378,982 Ott 3,885,369 Boarini 3,965,639 GangaRao 4,320,606 ______________________________________
None of these prior art devices show a prefabricated load-bearing wall panel which has a concrete slab secured to but spaced apart from the wall studs so that the studs are permitted to bend relative to the slab in the general plane of the panel, and so that the slab does not fail upon normal shear loading of the panel, and is able to sustain compressive and tensile stresses relative to the studs.